Fuses, which are commonly used as circuit protection devices, provide electrical connections between sources of electrical power and circuit components that are to be protected. One type of fuse includes a fusible element disposed within a hollow fuse body. Conductive terminals may be connected to each end of the fusible element through the fuse body to provide a means of connecting the fuse within a circuit.
Upon the occurrence of a specified fault condition in a circuit, such as an overcurrent condition, the fusible element of a fuse may melt or otherwise separate to interrupt current flow in the circuit path. Protected portions of the circuit are thereby electrically isolated and damage to such portions may be prevented or at least mitigated. However, after a fuse element melts, an electrical arc may form in an air gap between the newly separated ends of the fusible element. If not extinguished, this arc may cause further damage to the circuit by allowing unwanted current to flow to circuit components.
Additionally, the electrical arc may often cause the hollow fuse body to rupture, which may also cause damage to the circuit being protected and surrounding components.
Conventionally, the hollow fuse body is often filled with silica to assist in suppressing the electrical arc. Silica fillers, however, are required to be compacted in the hollow fuse body in order to provide adequate electrical arc quenching. Even where silica fillers are properly compacted, the silica may shift when the electrical arc burns (e.g., due to displacement forces created by the electrical arc, or the like). As a result, portions of the hollow fuse body may be exposed and the fuse body may rupture due to the electrical arc. Furthermore, fuses using conventional fillers often have lower breaking capacity (e.g., short circuit current ratings) and offer reduced overload protection than may be desired. For example, fuses where silica is used as the filler may not provide high enough breaking capacity due to poor silica compaction and may offer reduced overload protection due to a loss of functional energy (i.e., heat) to the high thermal conductivity filler material.
Thus, there is a need for low thermal conductivity fuse fillers that do not shift when an electrical arc burns. Additionally, there is a need for fuse fillers that provide increased breaking capacity and increased current overload protection.